Answer:
The heat causes the molecules on rubbing surfaces to move faster and have more energy.
Answer:
The value is 
Explanation:
From the question we are told that
The mass of the car is
The period of the circular motion is 
The radius is 
Generally the frequency of the circular motion is

=> 
=> 
<span>238,900 mi hope it helps :)</span>
Answer: 20 kgm/s
Explanation:
Given that M1 = M2 = 10kg
V1 = 5 m/s , V2 = 3 m/s
Since momentum is a vector quantity, the direction of the two object will be taken into consideration.
The magnitude of their combined
momentum before the crash will be:
M1V1 - M2V2
Substitute all the parameters into the formula
10 × 5 - 10 × 3
50 - 30
20 kgm/s
Therefore, the magnitude of their combined momentum before the crash will be 20 kgm/s
In a stationary situation, the weight of person is

This is the weight "felt" by the scale, which is basically the normal reaction applied by the scale on the person, and which uses the value of g (9.81) as reference to convert the weight (602.8 N) into a mass (62 kg).
When the person is in the elevator, the scale says 77 kg. The scale is still using the same value of conversion (9.81), so the apparent weight "felt" by the scale is

This is the normal reaction applied by the scale on the person, and which is directed upward. Besides this force, there is still the weight W of the person, acting downward. So, if we use Newton's second law:


where a is the acceleration of the elevator. If we solve for a, we find

The negative sign means the acceleration is in the opposite direction of g (which we take positive), so it means the elevator is going upward.